Requirement for transcription factor IIA (TFIIA)-TFIID recruitment by an activator depends on promoter structure and template competition.

AUTOR(ES)

Lieberman, P M

RESUMO

Different mechanisms of transcriptional activation may be required for distinct classes of promoters and cellular conditions. The Epstein-Barr virus (EBV)-encoded transcriptional activator Zta recruits the general transcription factors IID (TFIID) and IIA (TFIIA) to promoter DNA and induces a TATA box-binding protein (TBP)-associated factor-dependent footprint downstream of the transcriptional initiation site. In this study, we investigated the functional significance of TFIID-TFIIA (D-A complex) recruitment by Zta. Alanine substitution mutations in the Zta activation domain which eliminate the ability of Zta to stimulate the D-A complex were examined. These Zta mutants were defective in the ability to activate transcription from an EBV-derived promoter (BHLF1) but activated a highly responsive synthetic promoter (Z7E4T). Both the number of activator binding sites and the core promoter region contribute to the requirement for D-A complex recruitment. These functionally distinct core promoters had significant differences in affinity for TBP and TFIID binding. The D-A complex-recruiting activity of Zta was found to be important for promoter selection in the presence of a competitor template. Conditions which limit TFIID binding to the TATA element or compromise the ability of TFIIA to bind TBP required activator stimulation of the D-A complex. These results indicate that D-A complex recruitment is one of at least two activation pathways utilized by Zta and is the essential pathway for a subset of promoters and conditions which limit TFIID binding to the TATA element.

Documentos Relacionados

• Synergistic and promoter-selective activation of transcription by recruitment of transcription factors TFIID and TFIIB
• Requirement of TRAP/Mediator for Both Activator-Independent and Activator-Dependent Transcription in Conjunction with TFIID-Associated TAFIIs
• The functional subunit of a dimeric transcription activator protein depends on promoter architecture.
• A class of activation domains interacts directly with TFIIA and stimulates TFIIA-TFIID-promoter complex assembly.
• Human general transcription factor TFIIA: characterization of a cDNA encoding the small subunit and requirement for basal and activated transcription.